Clemens Eisserer wrote:
Hi,
I've created a library which has to use custom TableCellRenderers for
its tables.
I experienced a large performance difference between running my
application as Application inside an JFrame and as an JApplet.
Parented inside of the JFrame scrolling the table was smooth, however
scrolling inside the applet was slow, especially if the mouse is over
the table while scrolling.
I did some profiling with netbeans-profiler and found the root-cause:
BasicTableUI.paintCell->CellRendererPane.paintComponent->Container.validate->Component.updateCursorImmediatly->GlobalCursorManager.updateCursorImmediatly()->_updateCursor....
The updateCursorImmediatly was called both times about 16.000 times,
with JFrame it consumed 22% of the cycles which is already
inefficient.
As JApplet it calls into getLocationOnScreen() which calls down till
XBaseWindow.toOtherWindow even slower which is about as slow as
updating the Cursor itself, so as applet it consumes 48% of all EDT
cycles.
The DefaultTableCellRenderer simply overrides validate with an empty
method, therefor no such calls are done.
But why does CellRendererPane.paintComponent() call validate at all?
CellRendererPain takes an argument that dictates whether or not it
validates. In most cases it's told to validate by the caller since the
renderer may need to do layout on its children.
I suggest you override validate() on your custom renderer to do nothing,
the same way the DefaultTableCellRenderer does.
If it cannot be avoided, is there no way to cache stuff in
XBaseWindow.toOtherWindow at all?
You'll have to ask the AWT team about this. I've CC'd them.
Shannon
Thanks, lg Clemens
Very simple TableCellRenderer which triggers the slowness:
JLabel renderer = new JLabel();
public Component getTableCellRendererComponent(JTable table, Object
value,
boolean isSelected, boolean hasFocus, int row, int column) {
renderer.setText((String)value);
renderer.setOpaque(true);
return renderer;
}
--
Shannon Hickey
[EMAIL PROTECTED]
Swing Team - Sun Microsystems, Inc.
http://java.sun.com/javase/technologies/desktop
